It’s an old movie, I reckon between 60’s and 80’s, the main character is a scientist, doctor, I believe. The entire world is affected by an epidemia that sets the scientific community to a desperate effort to find solutions. Our brave character leaves home and works restlessly in his laboratory, along with his colleagues. However all efforts run useless while natural disasters also strike the world badly. At the end our scientist too gets sick because of the same epidemia he tried to combat, I remember his hair drops randomly leaving him strangely bald.
The final scene is when already ruined he returns home after some weeks or months and he finds it destroyed and some people living in the ruins, he tries to expel them, but they beg him to allow them to say, and offer him a fruit, which at that point is a very valuable possession, he decides to stay there with them, they cry hugging each other, and the film ends.
A voice or letters appear at the end stating that this film is released in order to remember the world the possible consequences of the questionable way we are managing the planet.